A problem in the field of semiconductors is the degradation of device performance by hot carrier aging (HCA). This is a particular concern with respect to smaller devices in which proportionally larger voltages are used. When such high voltages are used, charge carriers can be sufficiently energetic to enter an insulating layer and degrade device behavior. Various approaches to addressing HCA are, however, expensive because they typically complicate the fabrication process.
After contact holes are patterned in a field oxide, a conductive metal layer is deposited (i.e. a metallization layer) to connect integrated circuit components. Metallization materials typically include aluminum and copper, for example. Copper is a better conductor than aluminum and because of reductions needed for 0.25 .mu.m and sub 0.25 .mu.m devices, copper is preferred as the metallization material. Additionally, copper is resistant to electromigration and can be deposited at low temperatures. A copper metallization layer may be formed by electrodeposition or electroplating. For a multi-metallization level device, after each step of electroplating copper, the device is annealed in a nitrogen gas atmosphere (forming gas) to stabilize the copper layer.
After the final metallization layer is formed, i.e. after the final copper electroplating step and the forming gas annealing step, a protective or passivation layer (cap) is formed on the device. Then, the device can be further annealed in a forming gas or deuterium gas atmosphere to reduce hot carrier aging. U.S. Pat. No. 5,872,387 to Lyding et al., for example, discloses a method for treating a semiconductor device which includes a step of passivating the device with deuterium. Thus, conventional techniques, e.g. as discussed above, necessitate relatively extended time annealing due to the numerous forming gas annealing steps during the electroplating of the copper metallization layers, in combination with the final annealing step after the device is substantially complete.